The purpose of the Histology Core is to perform tissue processing and staining, immunohistochemistry, and in situ hybridization for Program investigators, this associates, and the Transgenic Core (Core B). Because each project and the Transgenic Core propose numerous experiments requiring histological processing of samples and microscopic detection techniques, the Histology Core will be staffed by a research technician and will occupy dedicated and equipped laboratory space. To expedite the processing of samples, the Core will be organized into functional sub- components, or laboratories, that are defined by the services provided. The Histology Laboratory will provide samples, cut sections, perform histological staining, and store tissue blocks. The Immunology laboratory will perform immunostaining, assist investigators in preparing immunoreagents, and maintain commonly used materials. The Molecular Biology Laboratory will be responsible for in situ hybridization procedures, including labeling probes and storing reagents. Most tissue and cells samples will be collected and submitted by personnel associated with the individual investigators and the Transgenic Core. Project and Core investigators or their associates will complete a Work Order form that will be used to catalogue the work requested and to record the date that each task is completed. The quality and results of analytical assays will be reviewed by Dr. Wilson with the Program Investigator or the co- investigator who is responsible for the experiment. Thus, the aim of this Core is to provide a center for correlative interactions among the Program investigators in histological studies of the skin and associated structures.